The average of 7 numbers is 50. The average of three of them is 40, while the average of the last three is 60. What must be the remaining number

• sum of last 3 numbers=180
  sum of other 3 numbers=120
  sum of all seven numbers=350
  thus,
  180+120+x=350
  x=50.
• 11 years agoHelpfull: Yes(5) No(1)
• (7*50)-(3*40)-(3*60)=50
• 11 years agoHelpfull: Yes(1) No(0)
• given that avg of 7 nos is 50..by that we come to know that each person approximately equal to 50..and in second statement the avg is decreased by each person 10...and in thrd statement is avg is increased by each person is 10........so by adding increase and decrease % of first and last 3 then the Answer will be 50....
• 10 years agoHelpfull: Yes(1) No(0)
• let the numbers be a,b,c,d,e.
  (a+b+c+d+e+f+g)/7 = 50
  (a+b+c+d+e+f+g) = 50*7 = 350
  (a+b+c)/3 = 40
  (a+b+c) = 40*3 = 120
  (e+f+g)/3 = 60
  (e+f+g) = 60*3 = 180
  120+d+180 = 350
  d = 350-120-180
  d = 50
• 6 years agoHelpfull: Yes(1) No(0)
• (x1+x2+x3+x4+x5+x6+x7)/7 = 50(given) =>x1+x2+x3+x4+x5+x6+x7 =350 (eq-1)
  
  let [(x1+x2+x3)/3] =40 => x1+x2+x3=120 (eq-2)
  [(x5+x6+x7)/3] =60 => x5+x6+x7=180 (eq-3)
  sub eq-3 in eq-1:-
  x1+x2+x3+x4 = 350-(x5+x6+x7)=350-180=170.(eq-4)
  now,sub eq-2 in eq-4:-
  x4 = 170-(x1+x2+x3)=170-120= 50.
  Hence the remaining number value is 50.
  
• 11 years agoHelpfull: Yes(0) No(0)
• remaining number={7*50-(3*40+3*60)}=350-300=50
• 11 years agoHelpfull: Yes(0) No(0)
• seven numbers avg is 50 means total of 7 numbers is 7*50=350
  first three numbers total is=3*40=120
  last theree numbers sum is=3*60=180
  so total of 6 numbers is=120+180=300
  so remaining num=350-300=50
  remaining num=50
• 9 years agoHelpfull: Yes(0) No(0)